The strongest punch from the storm hit during the heart of the morning commute, causing a mess for commuters and a nightmare for highway crews.

Some school districts, including Boston, were criticized for holding classes despite icy sidewalks and poorly plowed roads.

Boston public schools spokesman Lee McGuire said schools were kept open because the weather forecast was so fluid. The district said students whose parents kept them home Friday would be considered "constructively present" and their absences would be excused.

Charley Foley, a meteorologist at the National Weather Service in Taunton, said the higher snowfalls were caused by winds swirling around the storm that subtly changed course from the northeast to a more northerly direction. That allowed the storm to tap colder air from Canada, pick up moisture from the warmer ocean and dump snow on New England.